Adaptation of potato cultivars to low potassium supply in flowing solution culture

Three German potato cultivars (Tomensa, Producent and Linda) were grown in a growth chamber in tanks with flowing solutions containing K-concentrations of 5,20 and 80 μM to investigate and compare changes in K uptake efficiency (K-influx in particular) during their growth and to find reasons for different K responsiveness. Potato cultivars differed in their K response. Potato cv. Tomensa was more responsive than other cultivars. Both shoot and root growth rates of more responsive cv. Tomensa depended on solution K levels in the initial stage and were greater at higher K levels. Causes of high K responsiveness were high relative shoot growth rate, low root length/shoot weight ratio and low K uptake rate per unit root (K-influx) at low K supply, particularly in the initial stages of growth. Highly responsive cv. Tomensa adapted to low K supply by increasing K influx at low K concentration in solution but due to time lag to adapt to low K supply it left behind other cultivars in K requirement.